1. Field of the Invention
The present invention relates to a printing system, a printing apparatus, and a printing method configured to form an image on one sheet using a first toner and a second toner and by using a plurality of printing apparatuses and a program thereof.
2. Description of the Related Art
Recently, an electrophotographic apparatus that uses a clear toner, which is a special printing material, has been introduced. A clear toner is a transparent recording material which has a characteristic of adding a transparent image to images.
By using a clear toner like this, images can be expressed in various ways. Accordingly, additional values of a resulting output product may increase. A conventional electrophotographic apparatus is capable of generating an output product using a clear toner by using one electrophotographic apparatus including a mechanism or a method for adding a clear toner image to cyan, magenta, yellow, and black (CMYK) color toner images. However, in printing image data using a special printing material such as the clear toner, the conventional electrophotographic apparatus may consume more amount of toners for printing in total compared to conventional printing by four color toners.
In particular, if the above-described conventional recording apparatus is used in color printing, it is necessary to form a special printing material image on an intermediate transfer member on CMYK four color toner images that have been formed by the above-described conventional method, and transfer the images on a sheet. In other words, an amount of applied toner which is equivalent to an amount of toner necessary for printing for each electrophotographic process may increase. Accordingly, a large processing load may arise in each processing.
In order to solve the above-described problem, Japanese Patent Application Laid-Open No. 2007-011028 discusses a method for calculating the amount of applied recording material that can be recorded using a special printing material based on the amount of applied toner of CMYK four color toners.
However, if the amount of applied special printing material is calculated according to the method discussed in Japanese Patent Application Laid-Open No. 2007-011028, the resulting amount of applied special printing material may become “0” in some cases. More specifically, the amount of applied special printing material may become “0” if the total amount of applied toner of four color toners exceeds a total amount of toners that can be effectively fixed on a sheet and appropriately used on a printing apparatus. In this case, if a user has instructed printing that uses a special printing material, the printing that uses the special printing material instructed by the user cannot be executed. Accordingly, a visual effect produced by the special printing material on an output product may not be achieved.
In order to solve the above-described problem, a conventional method discussed in Japanese Patent Application Laid-Open No. 2008-139589, if it is determined that printing instructed by a user, which uses a special printing material, cannot be executed by one fixing operation, changes the method for forming a special printing material image. More specifically, the conventional method prints and fixes images using toners other than the special printing material and outputs a sheet having the fixed image. Further, the conventional method prints an image using the special printing material on the sheet having the printed toner images and fixes the image again. The printing method in which images are fixed twice is referred to as “2-pass printing”.
By using the 2-pass printing method, an image can be printed using an amount of the special printing material more than a predetermined amount of the special printing material, which is previously determined based on the total amount of applied recording material that can be used on a printing apparatus. Therefore, in this case, printing that uses the special printing material instructed by a user can be executed. Accordingly, a visual effect of the special printing material on an output product intended by the user can be achieved.
By introducing a method that uses a clear toner, a problem, such as restriction of the toner amount, can be solved. However, if a user of the printing apparatus who does not use the clear toner, the method compliant with a job using the clear toner may require unnecessary functions and adversely increase costs of manufacture of the apparatus.
In order to solve this problem, the following system may be useful. In this system, a printing apparatus that uses a color toner and another printing apparatus that uses a special printing material are provided separately from each other. Further, a paper discharge unit of a first printing apparatus which uses the color toner and a paper feed unit of a second printing apparatus which uses the special printing material, are connected to each other. Accordingly, an output product using the special printing material can be completely generated under central control of the system. For a user who desires to execute printing using the special printing material, the system allows the user to use both the printing apparatus that uses the color toner and the other printing apparatus that uses the special printing material. On the other hand, for another user who does not desire to execute a print job that uses the special printing material, the system allows the user to use the printing apparatus that uses the color toner only. By using the method in which two printing apparatuses having different functions are connected to each other, the system can print a job as desired by the user.
However, in the system including the first and the second printing apparatuses connected with each other, if a timing of end of generation of image data within the second printing apparatus becomes later than a timing of discharge of a sheet having image data printed thereon from the first printing apparatus, a phenomenon of overrun may occur. “Overrun” is a state when image data is printed, the timing of end of generation of image data becomes later than the printing start time, and the printing may be started using image data incompletely generated. To paraphrase this, the overrun refers to an operation failure in which the image data to be printed is not completely generated before starting printing. If an overrun occurs, the paper may be jammed or a print failure in which the image data is not printed in the middle of a sheet may arise.
If it takes a long time in generating or transferring data necessary for printing that uses a clear toner which is executed by the second printing apparatus (hereinafter simply referred to as “clear image data”), printing may not be executed at the appropriate timing in synchronization with the conveyance to the second printing apparatus of the sheet having an image of data generated and printed by the first printing apparatus.
In this case, if the first printing apparatus further prints an image on a next sheet using a color toner and feeds the next sheet to the second printing apparatus when the second printing apparatus cannot perform printing, the paper jam may occur.
If the sheet having color images printed thereon is conveyed to the second printing apparatus before clear image data is completely generated by the second printing apparatus and if the printing is started in order to prevent paper jam, the overrun may occur. In this case, the sheet may be discharged without printing the clear image data thereon, or, even if the clear image data is printed on the sheet, the clear image data may be printed at an inappropriate printing position or on a wrong page.